Direct Oxidation of H ₂ S by Air at Low Temperatures Using Catalysts Derived from Industrial Solid Waste

Abstract When modifying solid waste materials (raw sludges) that were collected from the water supply plant with zinc nitrate by the impregnation method, followed by calcining at 400 °C, the obtained sample (denoted as ZnO/VT‐400 catalyst) performed high activity toward H 2 S oxidation, with the H 2 S conversion () of ∼91% after a reaction time of 270 min. For such a process, the following catalytic conditions were found to be optimal for the installed lab‐scale model of H 2 S treatment: reaction temperature of 150 °C; inlet H 2 S concentration of 2000 ppm; total gas‐air flowrate of 0.75 L/min; and catalyst mass of 1.0 g. Moreover, the catalyst showed its cycling stability, with ≈ 89% after the 4 th cycle (after 32 h of use). The ZnO/VT‐400 sample mainly consisted of Fe 2 O 3 , small amounts of SiO 2 , and ZnO. These components existed in amorphous forms and were evenly distributed on the catalyst's surface. Two steps of the reaction process were proposed for the chemical mechanism of catalysis, including the chemisorption of H 2 S on the active sites, followed by oxidation with the formation of sulfur elements. The work has demonstrated the positive use of industrial solid waste to develop low‐cost and high‐performance catalysts for H 2 S removal from the air.